> Aren't tiling window managers the traditional ones?
No, why should they? Traditional mainly means what is established custom, not just what comes first or later. Floating Window Managment is around for decades, since the earliest generations of GUIs and everyone is using them today by default. Tilling back in the early days was a neccesarity, not a choice, and it was replaced fast, making it the loser of development. Later development made it a viable alternative to floating, but at this point floating was already dominating.
> The ability for one window to float over another was a later innovation
Kinda questionable. It seems MacOS had floating from the beginning. Windows was missing it in the first version, but added it in the second. But nur sure how widley used Windows was used at that time.